Network processor system including a central processor and at least one peripheral processor

ABSTRACT

A general purpose, software-controlled central processor (CP) can be augmented by a set of task specific, specialized peripheral processors (PPs). The central processor accomplishes its functions with the support of the PPs. Peripheral processors may include but are not limited to a packet parser, a packet deconstructor, a search engine, and a packet editor. At each step in the use of this network processor system, the central processor has an opportunity to intervene and modify the handling of the packet based on its interpretation of PP results. The programmable nature of the CP and the PPs provides the system with flexibility and adaptability.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of network processors, specificallynetwork processors adapted to perform packet processing.

2. Description of the Related Art

In the data networking field there exists a long felt need to providefaster packet processing using fewer system resources and more efficienthardware. Those of ordinary skill in the art have long realized that aprogrammable processing system can be readily adapted to provide packetprocessing. However, such systems are typically implemented in custom orsemi-custom application specific integrated circuits (ASICs) which aredifficult and costly to develop and produce. Furthermore, such ASICs arenot readily changeable in the event that packet configurations,processing requirements, or standards change over time.

What is needed is a rapidly adaptable packet processing system able tobe easily configured to perform a wide range of packet processing taskswithout redesign or reconstruction of the processor system hardwareitself.

SUMMARY

Presently disclosed is a general purpose, software-controlled centralprocessor augmented by a set of task specific, specialized peripheralprocessors (simply referred to as “peripherals”). The central processoraccomplishes its software-determined functions with the support of theperipheral processors. Peripheral processors may include but are notlimited to a packet parser, which provides the central processor with anumerical summary of the packet format; a packet deconstructor, whichextracts designated fields from the packet, the positions of which aredetermined by the central processor according to the packet format; asearch engine, which is supplied a lookup index by and returns itsresults to the central processor; and a packet editor which modifies thepacket as determined by the central processor using thepreviously-identified information from other peripherals.

At each step in the use of this network processor system, the centralprocessor has an opportunity to intervene and modify the handling of thepacket based on its current interpretation of peripheral processorresults. The programmable nature of the central processor and theperipheral processors provides the system with flexibility andadaptability. Rather than having to modify a circuit or system design inan ASIC or other complex hardware device, new packet processingapplications may be accommodated through the development of new softwareand its deployment in the central and/or peripheral processors.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be better understood and its numerousfeatures and advantages made apparent to those skilled in the art byreferencing the accompanying drawings.

FIG. 1 is a high-level block diagram of the central processor/peripheralprocessor architecture according to one embodiment of the presentinvention.

FIG. 2 is a flowchart of the sequence of events by which a packet isprocessed according to one embodiment of the present invention.

The use of the same reference symbols in different drawings indicatessimilar or identical items.

DETAILED DESCRIPTION

Architecture

The network packet processor system of one embodiment of the presentinvention comprises a central processor (CP) and a set of peripheralprocessors (PP). In some embodiments of this architecture, theperipheral processors each communicate only with the central processor;they do not communicate with each other. In other embodiments, the PPscan share information either passed from the CP or derived within one ormore PPs with other PPs. The CP acts as the coordinating and controllingprocessor while each peripheral processor performs specialized taskswith high efficiency. The advantage of this architecture is that theindividual processor (CP and PP) workflows, tasks, and functions arecompletely modularized and configurable by appropriate processorprogramming.

FIG. 1 shows a high-level block diagram of the presentcentral/peripheral processor system architecture 100 for packetprocessing. Central processor 110 receives packets through any of anumber of means well-known in the art. Central processor 110 performs,in some embodiments, preliminary format checking, e.g., checksumvalidation, and passes the packet or parts of the packet to one or moreperipheral processors for additional work. Central processor 110 maypass data to one or more peripheral processors 120, 130, 140, and 150 insequence, in parallel, or in a pipelined fashion.

Central processor 110 is a general purpose programmable processor, suchas (but not limited to) an embedded processor core available fromTensilica, Inc. of Santa Clara, Calif. or Advanced RISC Machines (ARM)Ltd. of Cambridge, England. In some embodiments of the presentinvention, the embedded core forming central processor 110 is part of anapplication specific integrated circuit (ASIC).

In one embodiment of the present invention, shown in FIG. 1, fourperipheral processors 120, 130, 140, and 150 are employed. One ofordinary skill in the art will readily see that fewer or more PPs may beemployed without deviating from the spirit of the present invention.Accordingly, the present architecture is not limited to a certain numberof peripheral processors.

Peripheral processors 120, 130, 140, and 150 may each be implementedindependently in any form of processing module or ASIC known in theelectronic arts. For instance, any PP may be a collection of discrete,fixed (hard-wired) logic, a programmable or fixed state machine, amicrosequencer or microprocessor, a stored program-controlled processorusing either ROM or RAM storage or a combination thereof, or ageneral-purpose, fully programmable computer. Any implementation formmay be selected according to the tasks and functions of each PP andnetwork packet processor system 100 overall. Accordingly, the presentinvention is not limited in the physical implementation of any PP.

In some embodiments of the present invention, central processor 110 andone or more PPs are contained in the same ASIC.

Sequence of Events

In the embodiment of FIG. 1, the four PPs are packet parser 120, packetdeconstructor 130, search engine 140, and packet editor 150. Eachperforms specific functions at the request of central processor 110 andreturns results to central processor 110.

Packets are received and delivered simultaneously to packet parser 120.A buffer (not shown) may also be employed to provide latencycompensation, as is well-known in the art. Packet error detectioncode(s), such as the well-known cyclic redundancy check (CRC) field, areverified if present. Reception errors are flagged and included as partof a status word that is associated with the packet by packet parser120.

The packet is deposited into a latency buffer primarily to allow aminimum amount of data to accumulate for address lookup purposes. Thelatency buffer makes the receive packet data available to packetdeconstructor 130 and central processor 110 prior to the packet beingstored in a central packet data buffer (not shown).

Packet parser 120 takes a quick look at the received packet and assignsa “vector” to the packet that indicates to central processor 110 inwhich of several categories (based on, e.g., packet formats) the packetbelongs. A vector, as used here, is an identifying number or data field,such as simple byte code “0xF8” (F8 in hexadecimal notation). The vectorcan be one or more bits, bytes, or words. This provides centralprocessor 110 a head start in the processing of the receive packet.Knowing the packet vector, central processor 110 knows where in thepacket the fields of interest are located without having to examine thepacket itself. This knowledge is stored in central processor 110, in oneembodiment, using templates that indicate the desired fields for eachvector, i.e., for each type of packet. Operationally, if the packetconforms to one of several expected formats as indicated by the vector,the appropriate processing template held within packet deconstructor 130is selected by central processor 110. Packet deconstructor 130 executesthe selected template by reading the required data directly from thelatency buffer using pointers maintained by the latency buffer.

Packet deconstructor PP 130 delivers one set of selected fields tocentral processor 110 and accumulates a (possibly different) set offields into a search argument that it delivers (in some embodiments)directly to search engine PP 140. In other embodiments, the accumulatedsearch argument is delivered to search engine 140 via central processor110.

In either event, the search argument is used to extract routinginformation, such as the destination port, MAC address, or IP address(as appropriate to the routing level of interest) from the routing datastructures, which in some embodiments consist of tables. Various typesof packet routing lookups can be performed by search engine 140, such asthe well-known OSI Layer 2, Layer 3, and/or Layer 4 lookups. The searchyields search results that are returned to central processor 110.Typically, only one of the lookups results in a destinationdetermination; the layer 2 destination address lookup, in particular,determines which lookup identifies the packet's next destination.Central processor 110 has the option of examining the search results andmodifying the destination returned by the lookups as necessary, in caseof error or exception.

Editor PP 150 uses the information derived from parser 120, packetdeconstructor 130, search engine 140, and central processor 110 tomodify the packet (especially its header) in order to guide the packetto its next destination. This is the last step of the well-knownrouting/switching function performed by most packet processing systems.

Before the packet is forwarded by the switch/router, it is stored(buffered) in a packet data buffer (not shown). Such storage, includingall necessary queuing, flow management, buffer management, retrieval andoutbound (egress) forwarding and the like, may be accomplished by any ofa number of means well-known in the packet processing and networkingarts. Accordingly, packet storage (and subsequent retrieval) will not befurther discussed herein.

FIG. 2 is a flowchart of the sequence of events discussed above. Packetprocessing 200 begins with packet reception 210 and buffering 220 toaccommodate latency. Packet parsing 230 is next accomplished todetermine a packet vector by which the packet is internally identified.

Processing coordination and control 240 evaluates the packet vector andpasses the packet (either directly or by reference) to packetdeconstructing step 250. Packet deconstructing 250 deconstructs thepacket into its constituent parts, e.g., header fields, quality ofservice (QoS) bits, packet data payload, etc. The results ofdeconstructing 250 are passed back to processing step 240 and, in someembodiments, directly to searching (lookup) step 260.

Lookup results from search step 260 are returned to processing step 240where they are used to control packet editing step 270. The revisedpacket is then sent for storage and forwarding 299 by means well-knownin the art.

At any time in process 200, processing step 240 may, upon evaluation ofthe results of any PP step 230, 250, 260, or 270, redirect or alter theprocessing scheme according to its own (i.e., the central processor's)programming. Such redirection may occur, for instance, on an error orexception condition, such as the failure of a packet to pass a CRC checkor the receipt of an illegal format.

ALTERNATE EMBODIMENTS

While central processor 110 is described as a single, monolithicprocessor, nothing in the architecture of the present invention solimits its implementation. In particular, central processor 110 can beformed as an interconnected network or mesh of two or more processorsacting in concert. These processors forming central processor 110 may beimplemented in the same ASIC or other integrated circuit device or onmultiple ASICs or other integrated circuit devices. Such multi-processorimplementations of a single processing function (such as that of centralprocessor 110) are well-known to those of ordinary skill in the art.

Furthermore, while central processor 110 may be implemented as one ormore interconnected processors, the peripheral processors, as a group,may also be implemented in one or more “sets” of PPs in order topipeline or parallel packet processing across multiple peripheral setsunder the control of a single central processor entity. As with centralprocessor 110, the above-described PPs may be implemented on one or moreASICs or other integrated circuit devices.

In a further alternative embodiment, central processor 110 and theperipheral processors (in one embodiment, PPs 120, 130, 140, and 150)share a common set of registers in order to speed up data transferbetween them and calculations using the same data. Some or all of theregisters used by central processor 110 and all or some of theperipheral processors may be logically mapped to the same memorylocations or otherwise shared by means long known in the computer andmicrocomputer/microprocessor arts.

The order in which the processing steps of any embodiment of the presentinvention are performed is purely illustrative in nature. In fact, thesesteps can be performed in any order or in parallel, unless otherwiseindicated by the present disclosure.

The method of the present invention may be performed in either hardware,software, or any combination thereof, as those terms are currently knownin the art. In particular, the present method may be carried out bysoftware, firmware, or microcode operating on a computer or computers ofany type. Additionally, software embodying the present invention may bein the form of computer instructions in any form (e.g., source code,object code, interpreted code, etc.) stored in any computer-readablemedium (e.g., ROM, RAM, magnetic media, punched tape or card, compactdisc (CD) in any form, DVD, etc.). Furthermore, such software may alsobe in the form of a computer data signal embodied in a carrier wave,such as that found within the well-known Web pages transferred amongcomputers connected to the Internet. Accordingly, the present inventionis not limited to any particular platform, unless specifically statedotherwise in the present disclosure.

While particular embodiments of the present invention have been shownand described, it will be apparent to those skilled in the art thatchanges and modifications may be made without departing from thisinvention in its broader aspect and, therefore, the appended claims areto encompass within their scope all such changes and modifications asfall within the true spirit of this invention.

1. A method of packet processing comprising: parsing a packet using afirst peripheral processor, said packet having a header portion, todetermine a vector; coordinating processing using said vector;deconstructing said packet header to form header data using a secondperipheral processor; searching one or more data structures based onsaid header data to produce search results using a third peripheralprocessor; and editing said packet based on said search results, saidheader data, and said vector using a fourth peripheral processor;wherein said deconstructing comprises forming a search argument, saidcoordinating comprises, storing data within a shared register setcoupled to each of said peripheral processors, sharing said data withsaid parsing, said deconstructing, said searching, and said editing,monitoring said deconstructing, said searching, and said editing, andoperating on said search argument to form a modified search argumentprior to said searching, and said searching uses said modified searchargument.
 2. The method of claim 1, further comprising buffering saidpacket before said parsing.
 3. An apparatus for packet processing,comprising: A first peripheral processor for parsing a packet, saidpacket having a header portion, to determine a vector; A secondperipheral processor for deconstructing said packet header to formheader data; A third peripheral processor for searching one or more datastructures based on said header data to produce search results; A fourthperipheral processor for editing said packet based on said searchresults, said header data, and said vector; A central processor tocoordinate said packet processing tasks using said vector; and A sharedregister set coupled to said peripheral processors and to said centralprocessor; wherein Said deconstructing comprises forming a searchargument; Said coordinating comprises, Storing data within said sharedregister set, Said central processor and said one or more peripheralprocessors share data using shared register set, Said central processormonitors said deconstructing, said searching, and said editingprocesses, and Operating on said search argument to form a modifiedsearch argument prior to said searching; and Said searching uses saidmodified search argument.
 4. The apparatus of claim 3, wherein saidcentral processor comprises a general purpose processor.
 5. Theapparatus of claim 3, wherein said central processor comprises amicrosequencer.
 6. The apparatus of claim 3, wherein said centralprocessor comprises more than one processor acting in concert.
 7. Theapparatus of claim 3, wherein one or more of said peripheral processorscomprise fixed logic circuits.
 8. The apparatus of claim 3, wherein oneor more of said peripheral processors comprise programmable logiccircuits.
 9. The apparatus of claim 3, wherein one or more of saidperipheral processors comprise a programmable state machine.
 10. Theapparatus of claim 3, wherein said central processor and at least oneperipheral processor together form at least a part of a singleapplication specific integrated circuit.
 11. A computer system forpacket processing, comprising computer instructions for: parsing apacket using a first peripheral processor, said packet having a headerportion, to determine a vector; coordinating processing using saidvector; deconstructing said packet header to form header data using asecond peripheral processor; searching one or more data structures basedon said header data to produce search results using a third peripheralprocessor; and editing said packet based on said search results, saidheader data, and said vector using a fourth peripheral processor;wherein said deconstructing comprises forming a search argument, saidcoordinating comprises, storing data within a shared register setcoupled to each of said peripheral processors, sharing said data withsaid parsing, said deconstructing, said searching, and said editing,monitoring said deconstructing, said searching, and said editing andoperating on said search argument to form a modified search argumentprior to said searching, and said searching uses said modified searchargument.
 12. The computer system of claim 11, further comprisingbuffering said packet before said parsing.
 13. A computer-readablestorage medium, comprising computer instructions for: parsing a packetusing a first peripheral processor, said packet having a header portion,to determine a vector; coordinating processing using said vector;deconstructing said packet header to form header data using a secondperipheral processor; searching one or more data structures based onsaid header data to produce search results using a third peripheralprocessor; and editing said packet based on said search results, saidheader data, and said vector using a fourth peripheral processor;wherein said deconstructing comprises forming a search argument, saidcoordinating comprises, storing data within a shared register setcoupled to each of said peripheral processors, sharing said data withsaid parsing, said deconstructing, said searching, and said editing,monitoring said deconstructing, said searching, and said editing, andoperating on said search argument to form a modified search argumentprior to said searching, and said searching uses said modified searchargument.
 14. The computer system of claim 13, further comprisingbuffering said packet before said parsing.
 15. A computer data signalembodied in a carrier wave, comprising computer instructions for:parsing a packet using a first peripheral processor, said packet havinga header portion, to determine a vector; coordinating processing usingsaid vector; deconstructing said packet header to form header data usinga second peripheral processor; searching one or more data structuresbased on said header data to produce search results using a thirdperipheral processor; editing said packet based on said search results,said header data, and said vector using a fourth peripheral processor;wherein said deconstructing comprises forming a search argument, saidcoordinating comprises, storing data within a shared register setcoupled to each of said peripheral processors, sharing said data withsaid parsing, said deconstructing, said searching, and said editing,monitoring said deconstructing, said searching, and said editing, andoperating on said search argument to form a modified search argumentprior to said searching, and said searching uses said modified searchargument.
 16. The computer system of claim 15, further comprisingbuffering said packet before said parsing.